Relation between the meteoroid mass, velocity, and fireball brightness. The symbol size is proportional to the maximum brightness. The meteoroid subsamples with masses >5 g and >0.5 kg are marked by hatching. The uncertainty of velocities is lower than 1 km s⁻¹. The uncertainty of masses is driven by the uncertainty of the luminous efficiency and may be about 30%. Moreover, the mass of small meteoroids may be underestimated by a factor of two, as explained in Sect. 3.3.6.